A very useful class. How much you take of this depends on what you're aiming for. Decorum is used partly to talk to people at the palace, and partly to raise Social Reputation. Refinement is used to determine how well Olive does in most Social endings, and it decides a few other endings. The best ending score wise, the Ruling Queen, requires her to have 800 Refinement.

Decorum raises at a decent rate, so it doesn't take long for it to max out. Refinement's raise is another story. Since it's a stat and not a skill, the raise rate is slow compared to most classes. This especially becomes a problem if you're going for the Ruling Queen ending mentioned above. It's recommended that you try to combine this with other Refinement bonuses if you do go for it, even though they are few.

If you aim for other endings that don't need Refinement, it's alright to ignore this class or use it only to max Decorum. Inspite of this class' comparatively lower cost, the slow raises make Refinement one of the costliest stats to raise, especially since it's the best conventional way to do it. Raising other stats is more beneficial in the long run in this case.